Even though you plugged into a 50 amp outlet with a 30 amps adapter, your max supply is 50 amps, or 6,000 watts. (Amperage times voltage equals wattage.) That would cause your 30 amp cord to get hot, and that is not a good idea. The alternate solution is keep your usage down to 30 amps or lower.
Also remember that a 50 amp outlet is actually two 50 amps services, or 100 amps total. Your RV was wired to take advantage of the 100 amps of service, so it is a good idea to use a 50 amp cord whenever possible.
Holiday Rambler Navigator DP, Hummer, and Honda VT1100C Shadow